CN114990276A - Method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron - Google Patents
Method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron Download PDFInfo
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- CN114990276A CN114990276A CN202210778400.XA CN202210778400A CN114990276A CN 114990276 A CN114990276 A CN 114990276A CN 202210778400 A CN202210778400 A CN 202210778400A CN 114990276 A CN114990276 A CN 114990276A
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- molten iron
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 454
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 209
- 238000000034 method Methods 0.000 title claims abstract description 66
- 230000003009 desulfurizing effect Effects 0.000 title claims abstract description 28
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 212
- 239000002131 composite material Substances 0.000 claims abstract description 123
- 239000000292 calcium oxide Substances 0.000 claims abstract description 106
- 235000012255 calcium oxide Nutrition 0.000 claims abstract description 106
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 102
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 101
- 230000023556 desulfurization Effects 0.000 claims abstract description 99
- 238000007670 refining Methods 0.000 claims abstract description 94
- 239000002994 raw material Substances 0.000 claims abstract description 74
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 52
- 239000011734 sodium Substances 0.000 claims abstract description 35
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims abstract description 32
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 28
- WETINTNJFLGREW-UHFFFAOYSA-N calcium;iron;tetrahydrate Chemical compound O.O.O.O.[Ca].[Fe].[Fe] WETINTNJFLGREW-UHFFFAOYSA-N 0.000 claims abstract description 28
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 28
- 239000010959 steel Substances 0.000 claims abstract description 28
- 238000009628 steelmaking Methods 0.000 claims abstract description 23
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 19
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000011574 phosphorus Substances 0.000 claims abstract description 19
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 19
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 18
- 239000011593 sulfur Substances 0.000 claims abstract description 18
- 235000017557 sodium bicarbonate Nutrition 0.000 claims abstract description 16
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims abstract description 16
- 235000019738 Limestone Nutrition 0.000 claims abstract description 12
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 12
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 12
- 239000006028 limestone Substances 0.000 claims abstract description 12
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims abstract description 11
- 239000004615 ingredient Substances 0.000 claims description 26
- 238000002156 mixing Methods 0.000 claims description 25
- 239000000843 powder Substances 0.000 claims description 22
- 238000000227 grinding Methods 0.000 claims description 20
- 238000002360 preparation method Methods 0.000 claims description 20
- 239000002245 particle Substances 0.000 claims description 18
- 239000008188 pellet Substances 0.000 claims description 16
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 7
- 235000010755 mineral Nutrition 0.000 claims description 7
- 239000011707 mineral Substances 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 239000000428 dust Substances 0.000 claims description 3
- 239000002893 slag Substances 0.000 abstract description 13
- 238000003723 Smelting Methods 0.000 abstract description 10
- 229910000805 Pig iron Inorganic materials 0.000 description 25
- 238000003825 pressing Methods 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 9
- 239000004484 Briquette Substances 0.000 description 8
- 239000003153 chemical reaction reagent Substances 0.000 description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 6
- 235000011941 Tilia x europaea Nutrition 0.000 description 6
- 239000004571 lime Substances 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 238000005096 rolling process Methods 0.000 description 6
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 238000004148 unit process Methods 0.000 description 2
- 208000005156 Dehydration Diseases 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- QCJQWJKKTGJDCM-UHFFFAOYSA-N [P].[S] Chemical compound [P].[S] QCJQWJKKTGJDCM-UHFFFAOYSA-N 0.000 description 1
- 235000012820 baking ingredients and mixes Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention relates to a method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron, belonging to the technical field of steel smelting. The method comprises the following steps: before molten iron enters a steel making furnace, adding a composite refining agent into the molten iron, and simultaneously performing pre-desulfurization and pre-dephosphorization at 1350-1480 ℃; the composite refining agent is prepared from the following raw materials: sinter and/or composite calcium ferrite; tailings and/or steel sheet; limestone and/or quicklime; and soda, baking soda and/or sodium silicate; each raw material contains Fe according to 2 O 3 The mass ratio of CaO to CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, preparing the materials. The method can realize high-efficiency desulfurization and dephosphorization at the same time, greatly reduce the sulfur and phosphorus load and the slag discharge in converter steelmaking, effectively shorten the smelting period, and has great market prospect and application value.
Description
Technical Field
The invention belongs to the technical field of steel smelting, and particularly relates to a method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron.
Background
The molten iron pretreatment refers to a smelting process adopted before molten iron enters a steel making furnace, and all tasks of steel making are usually completed in the steel making process in the converter in the traditional steel making method. However, as the iron and steel raw materials and fuels become increasingly depleted, the contents of phosphorus and sulfur in the raw materials and the fuels are high, so that the initial contents of phosphorus and sulfur in molten iron are increased; in addition, with the development of scientific and technical progress, the requirements of users on the quality and the performance of steel-making products are more and more strict, and the requirements of users can be met only by requiring that the content of impurities such as phosphorus and sulfur in steel is very low. In the conventional converter steelmaking method, due to high temperature and high oxidizability in the converter, the dephosphorization and desulfurization capability of the converter is limited. Therefore, in order to solve the contradictions, a molten iron pretreatment process is adopted between the modern blast furnace iron making and the converter steel making, and the molten iron before entering the converter for smelting is treated to remove impurity elements, so that the sources of steel smelting raw materials are enlarged, the quality of steel is improved, the varieties of the converter steel making are increased, and the technical and economic indexes are improved.
Sulfur and phosphorus are typical impurity elements in molten steel, and desulfurization and dephosphorization are one of main tasks of a steelmaking process. It is well known that thermodynamically, desulfurization requires a high temperature and a reducing atmosphere, while dephosphorization requires a low temperature and an oxidizing atmosphere. In view of the great difference in the above thermodynamic conditions, the pre-desulfurization and the pre-dephosphorization of molten iron are generally separately processed in two unit processes. The typical method is that after the blast furnace is tapped, the operation of pre-desulfurizing molten iron (KR and the like are common processes) is firstly carried out, for example, refer to Chinese patent application 201010167157.5, Chinese patent application 202010599572.1 and the like; then the dephosphorization of the molten iron is carried out or the dephosphorization task is directly completed in the converter, for example, see the Chinese patent application 202010660075.8. The pre-desulfurization and the pre-dephosphorization of the molten iron are respectively treated in different unit processes, which brings about a plurality of defects of large slag quantity, high discharge, long flow, low efficiency and the like for the steelmaking process. However, in view of the contradiction between the two thermodynamic conditions, no pretreatment process capable of simultaneously carrying out pre-desulfurization and pre-dephosphorization (pre-desulfurization and pre-dephosphorization) on the molten iron is seen in the actual production at present.
In view of the above, it is very desirable to provide a method for simultaneously performing preliminary desulfurization and preliminary dephosphorization of molten iron in a molten iron pretreatment process.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron. The method can realize high-efficiency pre-desulfurization and pre-dephosphorization in the molten iron pretreatment process, greatly reduce the sulfur and phosphorus load of converter steelmaking and the discharge of slag quantity, effectively shorten the smelting period, and has great market prospect and application value.
The invention provides a method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron, which comprises the following steps: before molten iron enters a steel making furnace, adding a composite refining agent into the molten iron, and simultaneously performing pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃;
the composite refining agent is prepared from the following raw materials:
sinter and/or composite calcium ferrite;
tailings and/or steel sheet;
limestone and/or quicklime; and
soda, baking soda and/or sodium silicate;
each raw material according to Fe contained 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, preparing the materials.
Preferably, the amount of the composite refining agent is 2-10% of the mass of the molten iron; and/or the time for simultaneously carrying out pre-desulfurization and pre-dephosphorization on the molten iron is 6-12 min.
Preferably, in the process of storing or transporting the molten iron, a molten iron tank car, a torpedo tank car or a KR device is used as a reactor, and a composite refining agent is added into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃; when the molten iron is simultaneously subjected to pre-desulfurization and pre-dephosphorization, the top of the molten iron tank car or the top of the torpedo tank car is provided with a dust removal device.
Preferably, the initial sulfur content of the molten iron is less than or equal to 0.12 percent, and the initial phosphorus content is less than or equal to 0.20 percent; after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the sulfur content in the molten iron is less than or equal to 0.042 percent, and the phosphorus content is less than 0.06 percent.
Preferably, after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the carbon content in the molten iron is 3-4 wt%.
Preferably, the composite refining agent contains mineral phase CaFe 2 O 4 、CaFe n Al 2-n O 4 And/or Na 2 CaAl 4 O 8 Wherein n is more than or equal to 0 and less than 2.
Preferably, the preparation of the composite refining agent comprises the following steps:
(1) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of CaO to CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(2) and grinding and uniformly mixing the ingredients to prepare powder, pellets or briquettes, thus obtaining the composite refining agent.
Preferably, the preparation of the composite refining agent comprises the following steps:
(a) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(b) roasting 20-50% of the mass of the ingredients at 800-1300 ℃ for 1-4 h to obtain a roasting raw material;
(c) and grinding and uniformly mixing the roasting raw material and the rest ingredients to prepare powder, pellets or briquettes, namely the composite refining agent.
Preferably, after the pre-dephosphorization and the pre-dephosphorization are simultaneously carried out on the molten iron, the desulfurization rate is not less than 60 percent, and the dephosphorization rate is not less than 70 percent.
Preferably, the particle size of the powder is 0.5-2 mm; or the particle size of the pellets or the briquettes is 10-20 mm.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) the inventionThe method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron can simultaneously realize high-efficiency desulfurization and dephosphorization in the molten iron pretreatment process by adopting a novel composite refining agent, wherein the desulfurization rate and the dephosphorization rate are respectively 50-70%, 66-80% and above, the sulfur and phosphorus load and the slag discharge of converter steelmaking are greatly reduced, the smelting period is effectively shortened, and the method has great market prospect and application value; the composite refining agent adopted by the invention takes sintered ore and/or composite calcium ferrite, tailings and/or steel rolling sheet iron, limestone and/or quicklime, soda and/or baking soda and/or sodium silicate as raw materials and Fe contained in the raw materials 2 O 3 、CaO、Al 2 O 3 With Na 2 O is prepared according to a specific proportion; the composite refining agent adopted by the invention can respectively obtain thermodynamic conditions beneficial to molten iron desulphurization and dephosphorization in different local areas in the same system, and make up the defects of respective local thermodynamic conditions by means of unified good kinetic conditions (quick lime dissolution and good slag fluidity), so that the method can simultaneously obtain higher molten iron desulphurization rate and dephosphorization rate.
(2) The research result of the invention shows that the method of the invention is used for pre-desulfurizing and pre-dephosphorizing molten iron with the initial [ S ] content less than or equal to 0.12 percent and the initial [ P ] content less than or equal to 0.20 percent, the [ S ] content of the molten iron is less than or equal to 0.042 percent and the [ P ] content is less than 0.06 percent after the pre-desulfurizing and pre-dephosphorizing molten iron, and the desulfurizing rate and the dephosphorizing rate are respectively 50-70 percent, 66-80 percent and more.
Drawings
FIG. 1 is a diagram of a process for preparing a composite refining agent used in some embodiments of the present invention.
FIG. 2 is a diagram of a process for preparing a composite refining agent for use in further embodiments of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron, which comprises the following steps: before molten iron enters a steel making furnace (such as a converter), adding a composite refining agent into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization at a temperature of 1350-1480 ℃ (such as 1350 ℃, 1360 ℃, 1370 ℃, 1380 ℃, 1390 ℃, 1400 ℃, 1410 ℃, 1420 ℃, 1430 ℃, 1440 ℃, 1450 ℃, 1460 ℃, 1470 ℃ or 1480 ℃); in the present invention, the specific operation before the molten iron enters the steel making furnace may be, for example, melting pig iron into molten iron, that is, obtaining molten iron for steel making; adding a composite refining agent into molten iron for steel making, and simultaneously performing pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃; specifically, for example, in the process of storing or transporting molten iron, a molten iron tank car, a torpedo tank car or a KR device is used as a reactor, and a composite refining agent is added into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization at 1350-1480 ℃; the method has no special requirements on other operating conditions for pre-desulfurization and pre-dephosphorization of the molten iron, and can be realized by adopting the conventional conditions; in the invention, the simultaneous pre-desulfurization and pre-dephosphorization of the molten iron refers to the simultaneous pre-desulfurization and pre-dephosphorization double-dehydration treatment in the molten iron pretreatment stage; the composite refining agent is prepared from the following raw materials: sinter and/or composite calcium ferrite; tailings (e.g., iron-containing tailings) and/or mill scale; limestone and/or quicklime; and soda and/or baking soda and/or sodium silicate (Na) 2 SiO 3 ) (ii) a Each raw material according to Fe contained 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1 (e.g., 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, or 8:1), CaO and Al 2 O 3 The mass ratio of (4-13): 1 (e.g., 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, or 13:1), Na 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1 (e.g., 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5: 1); according to the invention, the composite refining agent can be obtained by mixing the raw materials according to the mass ratio, or can be obtained by preparing the mixture into powder, pellets or briquettes.
The method can simultaneously realize high-efficiency pre-desulfurization and pre-dephosphorization in the molten iron pretreatment process; the method can create different oxygen potentials at different reaction points in the same reactor, and can dephosphorize under high oxygen potential and desulfurize under low oxygen potential; meanwhile, by means of the low-melting-point ore phase, excellent dynamic conditions are created to make up for the deficiency of thermodynamic conditions, and further, the pre-desulfurization and the pre-dephosphorization of the molten iron are efficiently realized at the same time; the method greatly reduces the sulfur and phosphorus load and the slag discharge in converter steelmaking, effectively shortens the smelting period, and has great market prospect and application value.
The composite refining agent adopted by the method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron can be sinter and/or composite calcium ferrite and is rich in Fe 2 O 3 The tailings and/or steel sheet rolled by steel, CaO/CaCO 3 、Na 2 CO 3 /NaHCO 3 /Na 2 SiO 3 Is taken as raw material or industrial solid waste rich in the above components or mineral phases is taken as raw material; the invention has no special limitation on the sources and components of the sinter, the composite calcium ferrite, the tailings (iron-containing tailings), the steel rolled sheet and the like, and the dosage of each raw material is determined according to the Fe contained in each raw material after each raw material with known components is adopted or the component content of the sinter, the composite calcium ferrite, the tailings, the steel rolled sheet and the like is obtained by the existing method 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, preparing the materials.
The composite refining agent adopted by the method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron in the invention and the traditional dephosphorizing agent contain CaO-SiO 2 -Fe 2 O 3 Compared with slag systems, the invention has lower melting point, extremely fast slag formation and better fluidity, effectively shortens the smelting period and has great market prospect and application value; compared with a refining agent (slag former) reported in the prior art, the refining agent (slag former) can only achieve a higher dephosphorization effect (see Chinese patent application 202111215491.8), or can only achieve a higher desulfurization effect (see Chinese patent application 202010599572.1), or achieve a poorer double-desulfurization effect, for example, Chinese patent application 201910396813.X discloses a desiliconization, desulfurization and dephosphorization reagent for molten iron pretreatment, the desiliconization, desulfurization and dephosphorization reagent is prepared by mixing iron ore and lime, and the main components are determined by mass parts as follows: 40-60 parts of Fe 2 O 3 30-50 parts of CaO and 2-4 parts of SiO 2 2-4 parts of MgO and 1-3 parts of Al 2 O 3 Although the desiliconization, desulfurization and dephosphorization reagent can realize desulfurization and dephosphorization at the same time, the desiliconization, desulfurization and dephosphorization reagent can only reach about 65 percent of desulfurization rate and about 50 percent of dephosphorization rate on molten iron with lower initial sulfur content and lower initial phosphorus content, and simultaneously has lower desulfurization and dephosphorization efficiency; as is well known, for molten iron with higher initial sulfur content and initial phosphorus content, if the difficulty of achieving good desulfurization and dephosphorization effects is higher, the desiliconization desulfurization and dephosphorization reagent in the patent application has lower desulfurization and dephosphorization efficiency for molten iron with higher initial sulfur content and initial phosphorus content; and the composite refining agent used in the method of the present invention is used for the initial [ S ]]Content is less than or equal to 0.12%, initial [ P ]]The molten iron with the content less than or equal to 0.20 percent is subjected to the preliminary desulfurization and the preliminary dephosphorization at the same time to obtain the S in the molten iron]The content is less than or equal to 0.042 percent and the content is P]Content (wt.)<0.06 percent, and the desulfurization rate and the dephosphorization rate are respectively 50 to 70 percent, 66 to 80 percent and more, which is a high efficiency for desulfurization and dephosphorization in the molten iron pretreatment process, and makes breakthrough progress in the aspects of the simultaneous predesulfurization and predephosphorization of the molten iron.
The method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron adopts the composite refining agent comprising sintered ore and/or composite calcium ferrite, tailings and/or steel sheet rolled by steel,Limestone and/or quicklime, soda and/or baking soda and/or sodium silicate as raw material and Fe contained 2 O 3 、CaO、Al 2 O 3 With Na 2 And O is prepared according to a specific proportion, preferably, the composite refining agent is prepared by roasting 20-50% of the ingredients, then grinding and uniformly mixing the roasted ingredients with the rest ingredients which are not roasted, so that the composite refining agent contains CaFe 2 O 4 、CaFe n Al 2-n O 4 And/or Na 2 CaAl 4 O 8 The equal mineral phases and the phase components in the raw materials can further improve the effects of pre-desulfurization and pre-dephosphorization of the molten iron; the composite refining agent adopted by the invention can be directly used as a product, other raw materials are not required to be added, and the composite refining agent is adopted to simultaneously pre-desulfurize and pre-dephosphorize molten iron, so that carbon preservation of the molten iron can be effectively realized, and after the sulfur-phosphorus double-dephosphorization of the molten iron is completed, the carbon content in the molten iron is 3-4 wt%.
According to some preferred embodiments, the composite refining agent is used in an amount of 2 to 10% (e.g., 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%) by mass of the molten iron; and/or the time for simultaneously carrying out pre-desulfurization and pre-dephosphorization on the molten iron is 6-12 min (for example, 6, 7, 8, 9, 10, 11 or 12 min).
According to some preferred embodiments, in the process of storing or transporting the molten iron, a molten iron tank car, a torpedo tank car or a KR device is used as a reactor, and a composite refining agent is added into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃; when the molten iron is simultaneously subjected to pre-desulfurization and pre-dephosphorization, the top of the molten iron tank car or the top of the torpedo tank car is provided with a dust removal device.
According to some preferred embodiments, the molten iron has an initial sulphur [ S ] content of 0.12% or less and an initial phosphorus [ P ] content of 0.20% or less; after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the sulfur [ S ] content in the molten iron is less than or equal to 0.042%, and the phosphorus [ P ] content in the molten iron is less than 0.06%, preferably, after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the sulfur [ S ] content in the molten iron is less than or equal to 0.04%, and the phosphorus [ P ] content in the molten iron is less than 0.06%.
According to some preferred embodiments, the carbon content in the molten iron is 3 to 4 wt% after the molten iron is simultaneously subjected to pre-desulfurization and pre-dephosphorization.
The composite refining agent adopted by the method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron adopts sintered ore and/or composite calcium ferrite; tailings and/or steel sheet; limestone and/or quicklime; and soda and/or baking soda and/or sodium silicate are used as raw materials, and a certain amount of mineral phase is necessarily contained in the composite refining agent; the invention has no special requirements on the type and content of the mineral phase contained in the composite refining agent.
According to some preferred embodiments, the composite refining agent contains mineral phase CaFe 2 O 4 、CaFe n Al 2-n O 4 And/or Na 2 CaAl 4 O 8 And the like, wherein n is more than or equal to 0 and less than 2; in the present invention, CaFe n Al 2-n O 4 Represented by CaFe 2 O 4 Some or all of Fe is replaced by Al, and may be referred to as Ca (Fe, Al) 2 O 4 。
According to some preferred embodiments, the raw materials for preparing the composite refining agent are according to Fe content 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.8-5): 1, preparing the materials.
According to some more preferred embodiments, the raw materials for preparing the composite refining agent are according to Fe content 2 O 3 The mass ratio of the CaO to the CaO is (2-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (1.2-5): 1, preparing the materials.
According to some preferred embodiments, the preparation of the composite refining agent comprises the steps of:
(1) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(2) grinding and uniformly mixing the ingredients to prepare powder, pellets or briquettes, namely the composite refining agent; a process diagram for the preparation of a composite refining agent for use in some embodiments of the present invention is shown, for example, in FIG. 1.
According to some preferred embodiments, the preparation of the composite refining agent comprises the steps of:
(a) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of CaO to CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(b) roasting 20-50% (e.g., 20%, 25%, 30%, 35%, 40%, 45% or 50%) of the mass of the ingredients at 800-1300 ℃ (e.g., 800 ℃, 900 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃ or 1300 ℃) for 1-4 h (e.g., 1, 1.5, 2, 2.5, 3, 3.5 or 4h) to obtain a roasting raw material;
(c) grinding and uniformly mixing the roasting raw material and the rest ingredients to prepare powder, pellets or briquettes, namely the composite refining agent; in the invention, the rest ingredients are ingredients which are not roasted and account for 50-80% of the total ingredients in the step (a); a schematic of the process for making the composite refining agent used in other embodiments of the invention is shown, for example, in FIG. 2.
The method and conditions for milling and blending in step (2) or step (c) are not particularly limited, so that the calcined raw material and the rest ingredients which are not calcined are fully milled and blended, and in some specific embodiments of the invention, the fully milling and blending operations may be, for example: for the product directly prepared into powder, the powder can be fully ground until the powder can pass through a screen with the same particle size as the powder, then the powder is uniformly mixed for 2-5 min by a stirrer, and finally the powder which meets the particle size requirement is obtained by passing through the screen with the same particle size as the powder; for preparing the pellets or briquettes, the pellets or briquettes are preferably fully ground to be capable of passing through a 200-mesh screen, then uniformly mixed for 2-5 min by a stirrer, and then pressed to obtain the pellets or briquettes with strength and/or granularity meeting the industrial application requirements.
The composite refining agent adopted by the method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron in the invention is more preferably roasted by 20-50% of the mass of the ingredients to obtain the material rich in CaFe 2 O 4 、CaFe n Al 2-n O 4 Equal ore phase roasting raw materials; the roasting temperature is 800-1300 ℃, and the roasting time is 1-4 h; and grinding and uniformly mixing the roasted raw material and the residual unbaked ingredients (accounting for 50-80% of the total weight of the ingredients) to prepare powder, pellets or briquettes, namely the composite refining agent, so that the method disclosed by the invention can be realized more favorably, and meanwhile, the high-efficiency pre-desulfurization and pre-dephosphorization are realized.
According to some preferred embodiments, after the molten iron is simultaneously subjected to the pre-dephosphorization and the pre-dephosphorization, the desulfurization degree is not less than 60%, and the dephosphorization degree is not less than 70%.
According to some preferred embodiments, the particle size of the powder is 0.5 to 2 mm; or the particle size of the pellets or the briquettes is 10-20 mm; the invention has no requirement on the shape of the pressing block and whether the shape of the pressing block is regular or not, and the pressing block is pressed by adopting a conventional die, for example, the pressing block is an ellipsoidal pressing block, the grain size of the ellipsoidal pressing block is 10-20 mm, which means that the average value of the long diameter and the short diameter of the ellipsoidal pressing block is within the range of 10-20 mm.
The invention also provides a composite refining agent, which is used for pre-desulfurizing and pre-dephosphorizing molten iron at the same time, and is prepared from the following raw materials: sinter and/or composite calcium ferrite; tailings (e.g., iron-containing tailings) and/or mill scale; limestone and/or quicklime; and soda and/or baking soda and/or sodium silicate; each raw material according to Fe contained 2 O 3 The mass ratio of CaO to CaO is (1-8): 1 (e.g., 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, or 8:1), CaO and Al 2 O 3 The mass ratio of (4-13): 1 (e.g., 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, 10.5:1, 11:1, 11.5:1, 12:1, 12.5:1, or 13:1), Na 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1 (e.g., 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, or 5: 1).
The invention also provides a preparation method of the composite refining agent, which comprises the following steps:
(1) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(2) and grinding and uniformly mixing the ingredients to prepare powder, pellets or briquettes, thus obtaining the composite refining agent.
The invention also provides another preparation method of the composite refining agent, which comprises the following steps:
(a) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of CaO to CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(b) roasting 20-50% of the mass of the ingredients at 800-1300 ℃ for 1-4 h to obtain a roasting raw material;
(c) and grinding and uniformly mixing the roasting raw material and the rest ingredients to prepare powder, pellets or briquettes, namely the composite refining agent.
The research result of the invention shows that for the molten iron with the initial [ S ] content of less than or equal to 0.12 percent and the initial [ P ] content of less than or equal to 0.20 percent, the [ S ] content of the molten iron is less than or equal to 0.04 percent and the [ P ] content is less than 0.06 percent after the molten iron is simultaneously subjected to the pre-dephosphorization and the pre-dephosphorization by the composite refining agent prepared from the steps (a) to (c), and the desulfurization rate and the dephosphorization rate are respectively 60 to 70 percent, 70 to 80 percent and more.
The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.
Example 1
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron (namely molten iron for steelmaking), the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a composite refining agent is added into the molten iron to simultaneously carry out pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃, so that the molten iron with the [ S ] content of 0.041 wt%, the [ P ] content of 0.050 wt% and the [ C ] content of 3.7 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, baking soda and steel sheet iron, fully grinding and uniformly mixing, and pressing into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, baking soda and rolled iron sheet contain Fe 2 O 3 The mass ratio of CaO to CaO is 2.6:1, and CaO to Al 2 O 3 In a mass ratio of 5.5:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 1.4: 1.
In this example, the desulfurization rate for the simultaneous pre-desulfurization and pre-dephosphorization of the molten iron was 52.9%, and the dephosphorization rate was 66.7%.
Example 2
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.15kg of a pig iron block with the initial [ C ] content of 4.5 wt%, the [ S ] content of 0.091 wt% and the [ P ] content of 0.17 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, then 148g of a composite refining agent is added into the molten iron, and pre-desulfurization and pre-dephosphorization are simultaneously carried out at 1410 ℃ for 10min, so that the molten iron with the [ S ] content of 0.04 wt%, the [ P ] content of 0.054 wt% and the [ C ] content of 4.0 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of limestone, sinter, soda and iron-containing tailings, fully grinding,After uniformly mixing, directly preparing the mixture into powder with the particle size of 1mm through a sieve, namely the composite refining agent; wherein, the raw materials of limestone, sinter, soda and iron-containing tailings contain Fe 2 O 3 The mass ratio of CaO to CaO is 2.3:1, and CaO to Al 2 O 3 In a mass ratio of 5.2:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 2.1: 1.
In this example, the desulfurization rate for the simultaneous pre-desulfurization and pre-dephosphorization of molten iron was 56%, and the dephosphorization rate was 68.2%.
Example 3
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, then 150g of a composite refining agent is added into the molten iron, and pre-desulfurization and pre-dephosphorization are simultaneously carried out at 1410 ℃ for 10min, so that the molten iron with the [ S ] content of 0.042 wt%, the [ P ] content of 0.045 wt% and the [ C ] content of 3.8 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, sodium silicate and steel sheet iron, fully grinding and uniformly mixing, and pressing into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, sodium silicate and steel rolling sheet contain Fe 2 O 3 The mass ratio of CaO to CaO is 1:1, and CaO to Al 2 O 3 In a mass ratio of 4:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 0.8: 1.
In this example, the desulfurization rate for the simultaneous pre-desulfurization and pre-dephosphorization of molten iron was 51.7%, and the dephosphorization rate was 70%.
Example 4
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with an initial [ C ] content of 4.3 wt%, an [ S ] content of 0.087 wt% and a [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a composite refining agent is added into the molten iron to simultaneously carry out pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃, so that the molten iron with the [ S ] content of 0.04 wt%, the [ P ] content of 0.039 wt% and the [ C ] content of 3.9 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, baking soda and steel sheet iron, fully grinding and uniformly mixing, and pressing into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, baking soda and rolled iron sheet contain Fe 2 O 3 The mass ratio of CaO to CaO is 8:1, and CaO to Al 2 O 3 In a mass ratio of 13:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 5: 1.
In this example, the desulfurization rate for the simultaneous pre-desulfurization and pre-dephosphorization of molten iron was 54%, and the dephosphorization rate was 74%.
Example 5
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron (namely molten iron for steelmaking), the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a composite refining agent is added into the molten iron to carry out pre-desulfurization and pre-dephosphorization at 1410 ℃ for 10min at the same time, so that the molten iron with the [ S ] content of 0.031 wt%, the [ P ] content of 0.041 wt% and the [ C ] content of 3.8 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, baking soda and ingredients of steel rolling scales, roasting 20% of the ingredients at 1100 ℃ for 2 hours to obtain a roasted raw material, fully grinding and uniformly mixing the roasted raw material and the rest 80% of the ingredients, and pressing the mixture into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, baking soda and rolled iron sheet contain Fe 2 O 3 The mass ratio of the CaO to the CaO is 2.6:1, and the CaO and the Al are 2 O 3 In a mass ratio of 5.5:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 1.4: 1.
In the embodiment, the desulfurization rate of the molten iron is 64.4 percent, and the dephosphorization rate is 73 percent.
Example 6
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.15kg of a pig iron block with the initial [ C ] content of 4.5 wt%, the [ S ] content of 0.091 wt% and the [ P ] content of 0.18 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, then 148g of a composite refining agent is added into the molten iron, and pre-desulfurization and pre-dephosphorization are simultaneously carried out at 1410 ℃ for 10min, so that the molten iron with the [ S ] content of 0.028 wt%, the [ P ] content of 0.047 wt% and the [ C ] content of 4.0 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials limestone, sinter, soda and iron-containing tailings as auxiliary materials, roasting 50% of the auxiliary materials at 800 ℃ for 4 hours to obtain roasted raw materials, fully grinding and uniformly mixing the roasted raw materials and the rest 50% of the auxiliary materials by mass, and directly preparing the mixture into powder with the particle size of 1mm through a sieve, namely the composite refining agent; wherein, the raw materials of limestone, sinter, soda and iron-containing tailings contain Fe according to the content 2 O 3 The mass ratio of the CaO to the CaO is 2.3:1, and the CaO and the Al are 2 O 3 In a mass ratio of 5.2:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 2.1: 1.
In the embodiment, the desulfurization rate of the molten iron is 69.2 percent and the dephosphorization rate is 74 percent.
Example 7
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with an initial [ C ] content of 4.3 wt%, an [ S ] content of 0.087 wt% and a [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a composite refining agent is added into the molten iron to simultaneously carry out pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃, so that the molten iron with the [ S ] content of 0.0348 wt%, the [ P ] content of 0.0375 wt% and the [ C ] content of 3.9 wt% is obtained.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, sodium silicate and steel rolled sheet for proportioning, roasting 30% of the mass of the proportioning at 1300 ℃ for 1h to obtain a roasted raw material, and then roasting the roasted raw materialFully grinding and uniformly mixing the roasted raw material and the rest 70% of the ingredients by mass, and pressing into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, sodium silicate and steel rolling sheet contain Fe 2 O 3 The mass ratio of the CaO to the CaO is 1:1, and the CaO to the Al are 2 O 3 In a mass ratio of 4:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 0.8: 1.
In this example, the desulfurization rate of the simultaneous pre-desulfurization and pre-dephosphorization of the molten iron was 60%, and the dephosphorization rate was 75%.
Example 8
A method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron comprises the following steps: 2.20kg of a pig iron block with an initial [ C ] content of 4.3 wt%, a [ S ] content of 0.087 wt% and a [ P ] content of 0.15 wt% was taken, the pig iron block was melted into molten iron, the temperature of the molten iron was controlled to 1410 ℃, and then 150g of a composite refining agent was added to the molten iron at 1410 ℃ to simultaneously perform pre-desulfurization and pre-dephosphorization for 10min, thereby obtaining molten iron with a [ S ] content of 0.0278 wt%, a [ P ] content of 0.033 wt% and a [ C ] content of 3.8 wt%.
The preparation of the composite refining agent adopted in the embodiment is as follows: taking raw materials of quicklime, composite calcium ferrite, baking soda and steel sheet for batching, roasting 40% of the batching by mass at 1200 ℃ for 2h to obtain a roasted raw material, fully grinding and uniformly mixing the roasted raw material and the rest 60% of the batching by mass, and pressing the mixture into an ellipsoidal briquette with the particle size of 15mm, namely the composite refining agent; wherein, the raw materials of quicklime, composite calcium ferrite, baking soda and rolled iron sheet contain Fe 2 O 3 The mass ratio of CaO to CaO is 8:1, and CaO to Al 2 O 3 In a mass ratio of 13:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 5: 1.
In this example, the desulfurization rate for the preliminary desulfurization and preliminary dephosphorization of molten iron was 68%, and the dephosphorization rate was 78%.
Comparative example 1
Taking 2.10kg of a pig iron block with the initial [ C ] content of 4.4 wt%, the [ S ] content of 0.081 wt% and the [ P ] content of 0.16 wt%, melting the pig iron block into molten iron, controlling the temperature of the molten iron to 1410 ℃, and then adding 150g of a slag former into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃ to obtain the molten iron with the [ S ] content of 0.075 wt%, the [ P ] content of 0.092 wt% and the [ C ] content of 2.8 wt%.
The preparation of the slagging agent used in this comparative example was: taking raw materials of lime and steel rolling iron sheets, fully grinding and uniformly mixing the raw materials, and pressing the mixture into an ellipsoidal briquette with the particle size of 15mm to obtain a slagging agent; wherein, the raw materials of lime and steel rolling iron sheet contain Fe 2 O 3 And proportioning the materials according to the mass ratio of the CaO of 5.6: 1.
In the comparative example, the desulfurization rate of the molten iron subjected to the simultaneous pre-desulfurization and pre-dephosphorization is only 7.4%, the desulfurization effect is basically not achieved, and the dephosphorization rate is 42.5%.
Comparative example 2
2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a slagging agent is added into the molten iron to simultaneously carry out pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃, so that the molten iron with the [ S ] content of 0.069 wt%, the [ P ] content of 0.06 wt% and the [ C ] content of 3.8 wt% is obtained.
The preparation of the slagging agent used in this comparative example was: taking raw material Fe 2 O 3 、CaO、Al 2 O 3 And Na 2 O, wherein Fe 2 O 3 The mass ratio of CaO to CaO is 2.6:1, and CaO to Al 2 O 3 In a mass ratio of 5.5:1 and Na 2 O and Al 2 O 3 The mass ratio of the components is 1.4:1, and the components are fully ground, uniformly mixed and pressed into an ellipsoidal briquette with the grain diameter of 15mm to obtain the slag former.
In the comparative example, the desulfurization rate of the molten iron simultaneous pre-desulfurization and pre-dephosphorization is 20.7%, the desulfurization effect is poor, and the dephosphorization rate is 60%.
Comparative example 3
2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, then 150g of a composite slagging agent is added into the molten iron, and pre-desulfurization and pre-dephosphorization are simultaneously carried out at 1410 ℃ for 10min, so that the molten iron with the [ S ] content of 0.084 wt%, the [ P ] content of 0.04 wt% and the [ C ] content of 3.9 wt% is obtained.
The composite slagging agent adopted in the comparative example is as follows: referring to the method of example 1 of Chinese patent application 202111215491.8, a red mud-based composite calcium ferrite is prepared, and then Fe is added simultaneously when molten iron is pre-desulfurized and pre-dephosphorized simultaneously 2 O 3 CaO, and red mud-based composite calcium ferrite to form Fe 2 O 3 + CaO + red mud-based composite slag former of composite calcium ferrite, wherein Fe 2 O 3 The content of the red mud-based composite calcium ferrite is 66.5 wt%, the content of CaO is 7.8 wt%, and the content of the red mud-based composite calcium ferrite is 25.7 wt%.
In the comparative example, the desulfurization rate of the molten iron simultaneous pre-desulfurization and pre-dephosphorization is 3.4%, the desulfurization effect is basically not achieved, and the dephosphorization rate is 73.3%.
Comparative example 4
2.20kg of a pig iron block with the initial [ C ] content of 4.3 wt%, the [ S ] content of 0.087 wt% and the [ P ] content of 0.15 wt% is taken, the pig iron block is melted into molten iron, the temperature of the molten iron is controlled to be 1410 ℃, and then 150g of a desulfurization and dephosphorization agent is added into the molten iron to simultaneously carry out pre-desulfurization and pre-dephosphorization for 10min at 1410 ℃, so that the molten iron with the [ S ] content of 0.074 wt%, the [ P ] content of 0.108 wt% and the [ C ] content of 3.5 wt% is obtained.
The preparation of the desulfurization and dephosphorization reagent adopted in the comparative example is as follows:
s1: grinding iron ore and lime to below 100 meshes by using a vibration mill;
s2: determining the iron ore and lime after being ground by S1 according to the mass parts of the main components as follows: 40 parts of Fe 2 O 3 50 parts of CaO and 2 parts of SiO 2 4 parts of MgO and 1 part of Al 2 O 3 And then mixing the iron ore and lime, uniformly mixing, and pressing into spherical particles with the diameter of 5-10mm by using a sample press under the pressure of 10MPa to obtain the desulfurization and dephosphorization reagent.
In the comparative example, the desulfurization rate of the simultaneous pre-desulfurization and pre-dephosphorization of the molten iron was 14.9%, and the dephosphorization rate was 28%.
The method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron in the comparative example does not have a good double-desulfurization effect under the condition that the initial sulfur content is 0.087 wt% and the initial phosphorus content is 0.15 wt%.
Table 1: the performance indexes of examples 1 to 8 and comparative examples 1 to 4.
The invention has not been described in detail and is in part known to those of skill in the art.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron is characterized by comprising the following steps of: before molten iron enters a steel making furnace, adding a composite refining agent into the molten iron, and simultaneously performing pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃;
the composite refining agent is prepared from the following raw materials:
sinter and/or composite calcium ferrite;
tailings and/or steel sheet;
limestone and/or quicklime; and
soda, baking soda and/or sodium silicate;
each raw material contains Fe according to 2 O 3 The mass ratio of CaO to CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, preparing the materials.
2. The method of claim 1, wherein:
the amount of the composite refining agent is 2-10% of the mass of the molten iron; and/or
The time for simultaneously carrying out pre-desulfurization and pre-dephosphorization on the molten iron is 6-12 min.
3. The method of claim 1, wherein:
in the process of storing or transporting molten iron, a molten iron tank car, a torpedo tank car or a KR device is used as a reactor, and a composite refining agent is added into the molten iron to simultaneously perform pre-desulfurization and pre-dephosphorization at the temperature of 1350-1480 ℃;
when the molten iron is simultaneously subjected to pre-desulfurization and pre-dephosphorization, the top of the molten iron tank car or the top of the torpedo tank car is provided with a dust removal device.
4. The method of claim 1, wherein:
the initial sulfur content of the molten iron is less than or equal to 0.12 percent, and the initial phosphorus content is less than or equal to 0.20 percent;
after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the sulfur content in the molten iron is less than or equal to 0.042 percent, and the phosphorus content is less than 0.06 percent.
5. The method of claim 1, wherein:
after the pre-desulfurization and the pre-dephosphorization are simultaneously carried out on the molten iron, the carbon content in the molten iron is 3-4 wt%.
6. The method according to any one of claims 1 to 5, characterized in that:
the composite refining agent contains mineral phase CaFe 2 O 4 、CaFe n Al 2-n O 4 And/or Na 2 CaAl 4 O 8 Wherein n is more than or equal to 0 and less than 2.
7. The method according to any one of claims 1 to 5, wherein the preparation of the composite refining agent comprises the steps of:
(1) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(2) and grinding and uniformly mixing the ingredients to prepare powder, pellets or briquettes, thus obtaining the composite refining agent.
8. The method according to any one of claims 1 to 5, wherein the preparation of the composite refining agent comprises the steps of:
(a) the raw materials for preparing the composite refining agent contain Fe 2 O 3 The mass ratio of the CaO to the CaO is (1-8): 1. CaO and Al 2 O 3 The mass ratio of (4-13): 1. na (Na) 2 O and Al 2 O 3 The mass ratio of (0.5-5): 1, burdening;
(b) roasting 20-50% of the mass of the ingredients at 800-1300 ℃ for 1-4 h to obtain a roasting raw material;
(c) and grinding and uniformly mixing the roasting raw material and the rest ingredients to prepare powder, pellets or briquettes, namely the composite refining agent.
9. The method of claim 8, wherein:
after the molten iron is simultaneously subjected to pre-dephosphorization and pre-dephosphorization, the desulfurization rate is not less than 60 percent, and the dephosphorization rate is not less than 70 percent.
10. The method of claim 8, wherein:
the particle size of the powder is 0.5-2 mm; or
The particle size of the pellets or the briquettes is 10-20 mm.
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| CN202210778400.XA CN114990276A (en) | 2022-07-04 | 2022-07-04 | Method for simultaneously pre-desulfurizing and pre-dephosphorizing molten iron |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5629611A (en) * | 1979-08-20 | 1981-03-25 | Nippon Steel Corp | Simultaneous dephosphorizing desulfurization of blast furnace molten pig iron |
| CN107849625A (en) * | 2016-01-05 | 2018-03-27 | 新日铁住金株式会社 | Dephosphorising agent, refining agent and the dephosphorization method of molten iron |
| CN114657326A (en) * | 2022-03-30 | 2022-06-24 | 北京科技大学 | Dephosphorization agent and application thereof |
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2022
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|---|---|---|---|---|
| JPS5629611A (en) * | 1979-08-20 | 1981-03-25 | Nippon Steel Corp | Simultaneous dephosphorizing desulfurization of blast furnace molten pig iron |
| CN107849625A (en) * | 2016-01-05 | 2018-03-27 | 新日铁住金株式会社 | Dephosphorising agent, refining agent and the dephosphorization method of molten iron |
| CN114657326A (en) * | 2022-03-30 | 2022-06-24 | 北京科技大学 | Dephosphorization agent and application thereof |
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| 张康晖等: "CaO-SiO_2-Al_2O_3-Na_2O-TiO_2-(MgO)渣系与碳饱和铁液间硫分配比的热力学模型", 《钢铁研究学报》 * |
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